A cable reel includes a flat cable having one end secured to a stationary member and the other end secured to a movable member so that the flat cable is reeled on or supplied from the movable member in response to a rotation of the movable member, so as to rotate the movable member by a predetermined amount, and the cable reel is used in a vehicle steering assembly, etc.
FIGS. 3 through 5 show a prior art cable reel of this type for use in a vehicle. FIG. 3 is an exploded perspective view, FIG. 4 is a longitudinal cross-sectional view, and FIG. 5 is a plan view in which a movable member is partly not shown. In these drawings, reference numeral 1 designates a movable member which includes a rotary cylinder 3 extending vertically at the center thereof and having a shaft insertion hole 2. A cylindrical holder 4 is provided outside the rotary cylinder 3. The holder 4 has a vertically extending slit 4a and a recess 4b offset from the inner surface thereof. The holder 4 is secured to a top plate of the movable member 1 and defines a predetermined space between the outer peripheral surface of the rotary cylinder 3 and itself.
Reference numeral 5 designates a flexible flat cable including an embedded conductive film. One end portion of the flat cable 5 passes through the slit 4a of the holder 4, and it is re-directed by turning a right angle in the recess 4b along a turning line of about 45 degrees and then extends to the exterior of the movable member 1. At the re-directing portion, the flat cable 5 is bifurcated along its length direction into two outlets 5a-5a which are re-directed individually so as to extend outwardly in an overlapping alignment. These outlets 5a-5a are conjoined by a snapping engagement and are sandwichingly held between first and second stoppers 6 and 7 secured to the top plate of the movable member 1. In this configuration, a tapered portion 6a of the first stopper 6 is inserted in the re-directing portions of the outlets 5a-5a.
Reference numeral 8 designates a stationary member which is provided with a center hole 9 which pivotably supports the rotary cylinder 3 of the movable member 1 in a snapping engagement therewith. The stationary member 8 has a vertical outer-limit peripheral wall 10 for storage of the flat cable 5. The outer-limit peripheral wall 10 has a guide portion 11 extending in the lower diagonal direction to guide the other end of the flat cable 5 once turned by a right angle inside the outer peripheral wall 10 to the exterior of the stationary member 8. The outer-most peripheral wall 10 is also provided with a positioning mechanism 13 having a gear 12 which is configured to rotate every predetermined angle by engagement with an engaging projection 14 extending from the outer peripheral wall of the movable member 1.
The cable reel is generally arranged as described above, and the movable member 1 is combined with a steering wheel of a vehicle steering assembly or other various devices while the stationary member 8 is combined with a bearing of a steering shaft. In this arrangement, when the steering wheel (movable member 1) is rotated in one direction, the flat cable 5 is reeled up toward the holder 4 of the movable member 1, and when the steering wheel is rotated in the opposite direction, the flat cable 5 is reeled off toward the outer-limit peripheral wall 10 of the stationary member 8. In either condition, electrical connection between the movable member 1 and the stationary member 8 is maintained via the flat cable 5. Further, since the gear 12 engages the projection 14 and is rotated thereby a predetermined angle upon every full rotation of the movable member 1, selected one of teeth of the gear 12 and a casing of the positioning mechanism may be marked with suitable indication in order to eliminate a difference between the rotating amounts in opposite directions of the flat cable 5 to prevent fracture or buckling of flat cable 5.
In the aforegoing prior art cable reel, however, the flat cable 5 is bifurcated in the length direction thereof before extended to the exterior of the movable member 1, and the respective outlets 5a-5a are re-directed individually so as to exhibit an overlapping alignment. This arrangement is certainly advantageous in that the diameter of a member (holder 4 in the aforegoing prior art) for winding the inner portion of the flat cable 5 thereof can be reduced because the width (shown at A in FIG. 5) of the inner portion of the flat cable 5 is about half the width of a non-bifurcated flat cable. However, the arrangement requires the manufacturing process of individually turning the bifurcated outlets of the flat cable 5 and two individual connectors for respective ends of the outlets 5a-5a for connection to an external device. This apparently increases the manufacturing cost.